This book constitutes the refereed proceedings of the First International Workshop on Knowledge Discovery from XML Documents, KDXD 2006, held in Singapore in conjunction with the 10th Pacific-Asia Conference on Knowledge Discovery and Data Mining (PAKDD 2006).

The 10 revised full papers presented together with 2 invited talks were carefully reviewed and selected from 26 submissions. The papers are organized in topical sections on XML data mining methods of classification, clustering and association; XML data reasoning and querying methods, query optimization; and on XML data applications of transportation and security.